Insect larvae and some fully developed insects, such as termites, are either blind or possess only simple eyes. Simple eyes can pretty much differentiate only between light and dark. Most adult insects, however, have compound eyes, which are equipped to distinguish colors.
The Compound Eye
Among compound-eye insects, though, the majority are bichromatic. This means they have just two types of color pigment receptors, and, as a result, they are not so good at distinguishing pure colors from mixtures of colors. Their color spectrum is limited.
Trichromatic insects, such as honeybees, have three types of pigment receptors, like we humans do. They can distinguish a wider spectrum of colors than bichromatic insects. However, their three pigment receptors do not coincide with ours.
Human Vision Vs. Insect Sight
The spectrum of colors visible to insects is a little higher in frequency than what we humans can see. The lowest frequency of color we see, red, is invisible to insects.
Conversely, while violet light is the highest frequency of color humans can detect on the electromagnetic spectrum, many insects can see a higher frequency of light invisible to us, ultraviolet light.
Ultraviolet light makes patterns on flowers, helping honeybees distinguish these flowers from others that to the human eye may look much the same. It makes intricate patterns on butterfly wings that look drab to our limited vision. Ultraviolet light also guides monarch butterflies in their extraordinary two thousand mile migrations.
We've developed instruments that help us to detect the presence of ultraviolet light, but we can only guess at what it looks like to those creatures that can really see it.